There are numerous publications concerning the recovery of energy from exhaust gases, for example of an internal combustion engine. Most publications do not address exhaust gas recirculation.
In some systems, the recovery of exhaust gas energy also takes place in connection with cooled exhaust gas recirculation, which is advantageous in itself.
Corresponding concepts from the company AVL List GmbH, Austria were presented at the Truck & Bus World Forum on 8 and 9 Dec. 2008 in Göteborg, Sweden. Similar concepts and systems have also been published by Cummins Inc., USA.
However, since exhaust gas recirculation is not carried out in all operating phases of internal combustion engines, exhaust gas recirculation heat exchangers or evaporators are typically not traversed constantly by exhaust gas. This means that, in general, no recovery of energy from exhaust gases is carried out in such operating phases in which no cooled exhaust gas recirculation takes place (for example, in idle phases of the internal combustion engine).
Even though operating phases with cooled exhaust gas recirculation are considerably prevalent, there is potential for improvement with regard to recovery of exhaust gas heat energy. Energy recovery carried out during cooled exhaust gas recirculation is often not efficient enough.